The Collaborative International Dictionary of English v.0.48:

Theodicy \The*od"i*cy\, n. [NL. theodicaea, fr. Gr. ? God + ?
   right, justice: cf. F. th['e]odic['e]e.]
   1. A vindication of the justice of God in ordaining or
      permitting natural and moral evil.
      [1913 Webster]

   2. That department of philosophy which treats of the being,
      perfections, and government of God, and the immortality of
      the soul. --Krauth-Fleming.
      [1913 Webster]

WordNet (r) 3.0 (2006):

theodicy
    n 1: the branch of theology that defends God's goodness and
         justice in the face of the existence of evil